Sika deer (Cervus nippon) invade farmlands and grazing areas, causing agricultural damage through feeding. We aimed to create an effective technology that utilizes the natural communication patterns of sika deer to regulate behavior and encourage escape responses. However, the vocalization characteristics of sika deer, particularly those related to alertness and escape, have not been fully clarified. This study examined how the acoustic characteristics of sika deer alarm calls differed according to the presence or absence of escape behaviors during alert states. Alarm calls were collected from mixed herds of male, female, and juvenile sika deer and analyzed. Vocalizations were converted into spectrograms using the acoustic analysis software Praat and analyzed based on 27 acoustic parameters, including call duration. Significant differences (P < 0.05) were revealed in the fundamental frequency (mean, minimum, and maximum), intensity (mean), formants 1 and 3, number of pulses, number of periods, fraction of locally unvoiced frames, number of voice breaks, and degree of voice breaks between groups with and without escape behavior. In particular, an increase of at least 280 Hz in the fundamental frequency (mean) of alarm calls increased by at least 280 Hz when escape behavior accompanied the alarm call.